AuOxFy- species (x + y = 2-5) are systematically studied using gradient corrected density functional theory. Their vertical detachment energies are larger than the electron affinity of halogen, suggesting them as a new class of superhalogen anions. Attempts have been made to tune the oxidation states of Au successively from +2 to +8 in AuOxFy-. However, AuOxFy- are stable only up to +5 oxidation state which is predicted to be the highest possible oxidation state of Au. Our calculations clearly show that AuOxFy- become unstable and tend to form (AuOx-2Fy-)O-2 complexes when the oxidation state of Au exceeds +5. (C) 2015 Elsevier B.V. All rights reserved.